Commit d6b9a81b authored by Anton Blanchard's avatar Anton Blanchard Committed by Benjamin Herrenschmidt

powerpc: IOMMU fault injection

Add the ability to inject IOMMU faults. We enable this per device
via a fail_iommu sysfs property, similar to fault injection on other
subsystems.

An example:

...
0003:01:00.1 Ethernet controller: Emulex Corporation OneConnect 10Gb NIC (be3) (rev 02)

To inject one error to this device:

echo 1 > /sys/bus/pci/devices/0003:01:00.1/fail_iommu
echo 1 > /sys/kernel/debug/fail_iommu/probability
echo 1 > /sys/kernel/debug/fail_iommu/times

As feared, the first failure injected on the be3 results in an
unrecoverable error, taking down both functions of the card
permanently:

be2net 0003:01:00.1: Unrecoverable error in the card
Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent a9803497
......@@ -331,4 +331,13 @@ config STRICT_DEVMEM
If you are unsure, say Y.
config FAIL_IOMMU
bool "Fault-injection capability for IOMMU"
depends on FAULT_INJECTION
help
Provide fault-injection capability for IOMMU. Each device can
be selectively enabled via the fail_iommu property.
If you are unsure, say N.
endmenu
......@@ -34,6 +34,9 @@ struct dev_archdata {
#ifdef CONFIG_EEH
struct eeh_dev *edev;
#endif
#ifdef CONFIG_FAIL_IOMMU
int fail_iommu;
#endif
};
struct pdev_archdata {
......
......@@ -34,6 +34,8 @@
#include <linux/iommu-helper.h>
#include <linux/crash_dump.h>
#include <linux/hash.h>
#include <linux/fault-inject.h>
#include <linux/pci.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/iommu.h>
......@@ -41,6 +43,7 @@
#include <asm/machdep.h>
#include <asm/kdump.h>
#include <asm/fadump.h>
#include <asm/vio.h>
#define DBG(...)
......@@ -79,6 +82,94 @@ static int __init setup_iommu_pool_hash(void)
}
subsys_initcall(setup_iommu_pool_hash);
#ifdef CONFIG_FAIL_IOMMU
static DECLARE_FAULT_ATTR(fail_iommu);
static int __init setup_fail_iommu(char *str)
{
return setup_fault_attr(&fail_iommu, str);
}
__setup("fail_iommu=", setup_fail_iommu);
static bool should_fail_iommu(struct device *dev)
{
return dev->archdata.fail_iommu && should_fail(&fail_iommu, 1);
}
static int __init fail_iommu_debugfs(void)
{
struct dentry *dir = fault_create_debugfs_attr("fail_iommu",
NULL, &fail_iommu);
return IS_ERR(dir) ? PTR_ERR(dir) : 0;
}
late_initcall(fail_iommu_debugfs);
static ssize_t fail_iommu_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", dev->archdata.fail_iommu);
}
static ssize_t fail_iommu_store(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
{
int i;
if (count > 0 && sscanf(buf, "%d", &i) > 0)
dev->archdata.fail_iommu = (i == 0) ? 0 : 1;
return count;
}
static DEVICE_ATTR(fail_iommu, S_IRUGO|S_IWUSR, fail_iommu_show,
fail_iommu_store);
static int fail_iommu_bus_notify(struct notifier_block *nb,
unsigned long action, void *data)
{
struct device *dev = data;
if (action == BUS_NOTIFY_ADD_DEVICE) {
if (device_create_file(dev, &dev_attr_fail_iommu))
pr_warn("Unable to create IOMMU fault injection sysfs "
"entries\n");
} else if (action == BUS_NOTIFY_DEL_DEVICE) {
device_remove_file(dev, &dev_attr_fail_iommu);
}
return 0;
}
static struct notifier_block fail_iommu_bus_notifier = {
.notifier_call = fail_iommu_bus_notify
};
static int __init fail_iommu_setup(void)
{
#ifdef CONFIG_PCI
bus_register_notifier(&pci_bus_type, &fail_iommu_bus_notifier);
#endif
#ifdef CONFIG_IBMVIO
bus_register_notifier(&vio_bus_type, &fail_iommu_bus_notifier);
#endif
return 0;
}
/*
* Must execute after PCI and VIO subsystem have initialised but before
* devices are probed.
*/
arch_initcall(fail_iommu_setup);
#else
static inline bool should_fail_iommu(struct device *dev)
{
return false;
}
#endif
static unsigned long iommu_range_alloc(struct device *dev,
struct iommu_table *tbl,
unsigned long npages,
......@@ -107,6 +198,9 @@ static unsigned long iommu_range_alloc(struct device *dev,
return DMA_ERROR_CODE;
}
if (should_fail_iommu(dev))
return DMA_ERROR_CODE;
/*
* We don't need to disable preemption here because any CPU can
* safely use any IOMMU pool.
......
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